A statistical network analysis of the HIV/AIDS epidemics in Cuba

The Cuban contact-tracing detection system set up in 1986 allowed the reconstruction and analysis of the sexual network underlying the epidemic (5,389 vertices and 4,073 edges, giant component of 2,386 nodes and 3,168 edges), shedding light onto the spread of HIV and the role of contact-tracing. Clustering based on modularity optimization provides a better visualization and understanding of the network, in combination with the study of covariates. The graph has a globally low but heterogeneous density, with clusters of high intraconnectivity but low interconnectivity. Though descriptive, our results pave the way for incorporating structure when studying stochastic SIR epidemics spreading on social networks

Pathological Angiogenesis Requires Syndecan-4 for Efficient VEGFA-Induced VE-Cadherin Internalization

Objective: VEGFA (Vascular endothelial growth factor A) and its receptor VEGFR2 (vascular endothelial growth factor receptor 2) drive angiogenesis in several pathologies, including diabetic retinopathy, wet age-related macular degeneration, and cancer. Studies suggest roles for HSPGs (heparan sulfate proteoglycans) in this process, although the nature of this involvement remains elusive. Here, we set to establish the role of the HSPG SDC4 (syndecan-4) in pathological angiogenesis. Approach and Results: We report that angiogenesis is impaired in mice null for SDC4 in models of neovascular eye disease and tumor development. Our work demonstrates that SDC4 is the only SDC whose gene expression is upregulated during pathological angiogenesis and is selectively enriched on immature vessels in retinas from diabetic retinopathy patients. Combining in vivo and tissue culture models, we identified SDC4 as a downstream mediator of functional angiogenic responses to VEGFA. We found that SDC4 resides at endothelial cell junctions, interacts with vascular endothelial cadherin, and is required for its internalization in response to VEGFA. Finally, we show that pathological angiogenic responses are inhibited in a model of wet age-related macular degeneration by targeting SDC4. Conclusions: We show that SDC4 is a downstream mediator of VEGFA-induced vascular endothelial cadherin internalization during pathological angiogenesis and a potential target for antiangiogenic therapies

Pathological Angiogenesis Requires Syndecan-4 for Efficient VEGFA-Induced VE-Cadherin Internalization.

Objective: VEGFA (Vascular endothelial growth factor A) and its receptor VEGFR2 (vascular endothelial growth factor receptor 2) drive angiogenesis in several pathologies, including diabetic retinopathy, wet age-related macular degeneration, and cancer. Studies suggest roles for HSPGs (heparan sulfate proteoglycans) in this process, although the nature of this involvement remains elusive. Here, we set to establish the role of the HSPG SDC4 (syndecan-4) in pathological angiogenesis. / Approach and Results: We report that angiogenesis is impaired in mice null for SDC4 in models of neovascular eye disease and tumor development. Our work demonstrates that SDC4 is the only SDC whose gene expression is upregulated during pathological angiogenesis and is selectively enriched on immature vessels in retinas from diabetic retinopathy patients. Combining in vivo and tissue culture models, we identified SDC4 as a downstream mediator of functional angiogenic responses to VEGFA. We found that SDC4 resides at endothelial cell junctions, interacts with vascular endothelial cadherin, and is required for its internalization in response to VEGFA. Finally, we show that pathological angiogenic responses are inhibited in a model of wet age-related macular degeneration by targeting SDC4. / Conclusions: We show that SDC4 is a downstream mediator of VEGFA-induced vascular endothelial cadherin internalization during pathological angiogenesis and a potential target for antiangiogenic therapies

ERP evidence suggests executive dysfunction in ecstasy polydrug users

Background: Deficits in executive functions such as access to semantic/long-term memory have been shown in ecstasy users in previous research. Equally, there have been many reports of equivocal findings in this area. The current study sought to further investigate behavioural and electro-physiological measures of this executive function in ecstasy users. Method: Twenty ecstasy–polydrug users, 20 non-ecstasy–polydrug users and 20 drug-naïve controls were recruited. Participants completed background questionnaires about their drug use, sleep quality, fluid intelligence and mood state. Each individual also completed a semantic retrieval task whilst 64 channel Electroencephalography (EEG) measures were recorded. Results: Analysis of Variance (ANOVA) revealed no between-group differences in behavioural performance on the task. Mixed ANOVA on event-related potential (ERP) components P2, N2 and P3 revealed significant between-group differences in the N2 component. Subsequent exploratory univariate ANOVAs on the N2 component revealed marginally significant between-group differences, generally showing greater negativity at occipito-parietal electrodes in ecstasy users compared to drug-naïve controls. Despite absence of behavioural differences, differences in N2 magnitude are evidence of abnormal executive functioning in ecstasy–polydrug users

Supersymmetric mass spectra and the seesaw type-I scale

We calculate supersymmetric mass spectra with cMSSM boundary conditions and a type-I seesaw mechanism added to explain current neutrino data. Using published, estimated errors on SUSY mass observables for a combined LHC+ILC analysis, we perform a theoretical $\chi^2$ analysis to identify parameter regions where pure cMSSM and cMSSM plus seesaw type-I might be distinguishable with LHC+ILC data. The most important observables are determined to be the (left) smuon and selectron masses and the splitting between them, respectively. Splitting in the (left) smuon and selectrons is tiny in most of cMSSM parameter space, but can be quite sizeable for large values of the seesaw scale, $m_{SS}$. Thus, for very roughly $m_{SS} \ge 10^{14}$ GeV hints for type-I seesaw might appear in SUSY mass measurements. Since our numerical results depend sensitively on forecasted error bars, we discuss in some detail the accuracies, which need to be achieved, before a realistic analysis searching for signs of type-I seesaw in SUSY spectra can be carried out.Comment: 17 pages, 7 figure

Presynaptic partner selection during retinal circuit reassembly varies with timing of neuronal regeneration in vivo

Whether neurons can restore their original connectivity patterns during circuit repair is unclear. Taking advantage of the regenerative capacity of zebrafish retina, we show here the remarkable specificity by which surviving neurons reassemble their connectivity upon regeneration of their major input. H3 horizontal cells (HCs) normally avoid red and green cones, and prefer ultraviolet over blue cones. Upon ablation of the major (ultraviolet) input, H3 HCs do not immediately increase connectivity with other cone types. Instead, H3 dendrites retract and re-extend to contact new ultraviolet cones. But, if regeneration is delayed or absent, blue-cone synaptogenesis increases and ectopic synapses are made with red and green cones. Thus, cues directing synapse specificity can be maintained following input loss, but only within a limited time period. Further, we postulate that signals from the major input that shape the H3 HC's wiring pattern during development persist to restrict miswiring after damage

Baryonic Popcorn

In the large N limit cold dense nuclear matter must be in a lattice phase. This applies also to holographic models of hadron physics. In a class of such models, like the generalized Sakai-Sugimoto model, baryons take the form of instantons of the effective flavor gauge theory that resides on probe flavor branes. In this paper we study the phase structure of baryonic crystals by analyzing discrete periodic configurations of such instantons. We find that instanton configurations exhibit a series of "popcorn" transitions upon increasing the density. Through these transitions normal (3D) lattices expand into the transverse dimension, eventually becoming a higher dimensional (4D) multi-layer lattice at large densities. We consider 3D lattices of zero size instantons as well as 1D periodic chains of finite size instantons, which serve as toy models of the full holographic systems. In particular, for the finite-size case we determine solutions of the corresponding ADHM equations for both a straight chain and for a 2D zigzag configuration where instantons pop up into the holographic dimension. At low density the system takes the form of an "abelian anti-ferromagnetic" straight periodic chain. Above a critical density there is a second order phase transition into a zigzag structure. An even higher density yields a rich phase space characterized by the formation of multi-layer zigzag structures. The finite size of the lattices in the transverse dimension is a signal of an emerging Fermi sea of quarks. We thus propose that the popcorn transitions indicate the onset of the "quarkyonic" phase of the cold dense nuclear matter.Comment: v3, 80 pages, 18 figures, footnotes 5 and 7 added, version to appear in the JHE

An Integrative Analysis Uncovers a New, Pseudo-Cryptic Species of Amazonian Marmoset (Primates: Callitrichidae: \u3cem\u3eMico\u3c/em\u3e) from the Arc of Deforestation

Amazonia has the richest primate fauna in the world. Nonetheless, the diversity and distribution of Amazonian primates remain little known and the scarcity of baseline data challenges their conservation. These challenges are especially acute in the Amazonian arc of deforestation, the 2500 km long southern edge of the Amazonian biome that is rapidly being deforested and converted to agricultural and pastoral landscapes. Amazonian marmosets of the genus Mico are little known endemics of this region and therefore a priority for research and conservation efforts. However, even nascent conservation efforts are hampered by taxonomic uncertainties in this group, such as the existence of a potentially new species from the Juruena–Teles Pires interfluve hidden within the M. emiliae epithet. Here we test if these marmosets belong to a distinct species using new morphological, phylogenomic, and geographic distribution data analysed within an integrative taxonomic framework. We discovered a new, pseudo-cryptic Mico species hidden within the epithet M. emiliae, here described and named after Horacio Schneider, the pioneer of molecular phylogenetics of Neotropical primates. We also clarify the distribution, evolutionary and morphological relationships of four other Mico species, bridging Linnean, Wallacean, and Darwinian shortfalls in the conservation of primates in the Amazonian arc of deforestation

Gate-controlled Guiding of Electrons in Graphene

Ballistic semiconductor structures have allowed the realization of optics-like phenomena in electronics, including magnetic focusing and lensing. An extension that appears unique to graphene is to use both n and p carrier types to create electronic analogs of optical devices having both positive and negative indices of refraction. Here, we use gate-controlled density with both p and n carrier types to demonstrate the analog of the fiber-optic guiding in graphene. Two basic effects are investigated: (1) bipolar p-n junction guiding, based on the principle of angle-selective transmission though the graphene p-n interface, and (2) unipolar fiber-optic guiding, using total internal reflection controlled by carrier density. Modulation of guiding efficiency through gating is demonstrated and compared to numerical simulations, which indicates that interface roughness limits guiding performance, with few-nanometer effective roughness extracted. The development of p-n and fiber-optic guiding in graphene may lead to electrically reconfigurable wiring in high-mobility devices.Comment: supplementary materal at http://marcuslab.harvard.edu/papers/OG_SI.pd